为什么ADB命令会中断bash脚本循环？ [英] Why does ADB commands break a bash script loop?

问题描述

当从shell脚本循环中运行多个adb命令时，我注意到一个问题，大多数命令没有执行。

I'm noticing a problem when running multiple adb commands from a shell script loop most of the commands does not execute.

这是示例脚本。

脚本名称： adbscript.sh ：

#!/bin/bash

devicecount=0
while read device; do
    ((devicecount++))
    serialno="NA"
    appinstallcount="NA"
    echo "Processing Device #$devicecount: $device"
    # serialno=$(adb -s $device shell getprop ro.serialno)
    # appinstallcount=$(adb -s $device shell pm list packages | wc -l)
    echo -e "Device: $device | Serialno: $serialno | Apps installed: $appinstallcount\n"
done < <(adb devices | egrep "\bdevice\b" | awk '{print $1}')
echo "Finished."

带有adb命令的输出已注释掉

我已连接5台设备。从bash文件运行时，如果没有 adb 命令，则为输出。依次遍历5个循环。

I have 5 devices connected. When running from the bash file without theadb commands this is the output. It iterates through each of the 5 loops.

Processing Device #1: 192.168.15.93:5123
Device: 192.168.15.93:5123 | Serialno: NA | Apps installed: NA

Processing Device #2: 192.168.15.95:5123
Device: 192.168.15.95:5123 | Serialno: NA | Apps installed: NA

Processing Device #3: emulator-5554
Device: emulator-5554 | Serialno: NA | Apps installed: NA

Processing Device #4: 31005c77c8cfb200
Device: 31005c77c8cfb200 | Serialno: NA | Apps installed: NA

Processing Device #5: 98883837594d4f5453
Device: 98883837594d4f5453 | Serialno: NA | Apps installed: NA

Finished.

带循环的输出包含 ADB 命令

Output with loop containing ADB commands

取消对 adb shell 命令的注释时，它只能正确地迭代第一个循环的行。这是未注释 adb 命令的输出：

When the adb shell command is uncommented it only properly iterates lines of the first loop. This is the output with the adb command uncommented:

Processing Device #1: 192.168.15.93:5123
Device: 192.168.15.93:5123 | Serialno: 98883837594d4f5453 | Apps installed: 442

Finished.

有人可以解释这种现象吗？要处理所有行和所有循环，必须做什么？

Can someone explain this behavior and what would have to be done to have all the lines and all the loops processed?

顺便说一下，这是提供给脚本的输出（一个线性命令和输出）：

By the way, this is the output supplied to the script (one liner command and output):

$ adb devices | egrep "\bdevice\b" | awk '{print $1}'
192.168.15.93:5123
192.168.15.95:5123
emulator-5554
31005c77c8cfb200
98883837594d4f5453

推荐答案

adb shell 将stdin连接到在设备上运行的命令，通常会消耗标准输入，直到达到EOF。因此，这些命令占用了设备的所有其余名称，导致循环退出。

adb shell connects stdin to the command running on the device, which will generally consume stdin until a EOF is reached. So these commands consume all of the rest of your device names, causing the loop to exit.

运行 adb stdin重定向，这样他们就可以立即获得EOF，而不会弄乱您要循环播放的内容：

Run adb with a stdin redirection, so they get an immediate EOF without messing with what you're trying to loop over:

serialno=$(adb </dev/null -s $device shell getprop ro.serialno)
appinstallcount=$(adb </dev/null -s $device shell pm list packages | wc -l)

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